Guest book idea - great because you can get a photo of everyone at the wedding and get some advice for a scrapbook. Such a funny idea. It'd be fun to combine this with a photo booth. A photo booth guest book.
Message in a bottle guest book (people can write messages of their well wishes, or a piece of advice, or answer a question you ask them. For example, what is your favorite memory of the bride and groom or what should we name our first child, etc.
Caramel Against Dark Long hair can easily showcase hair color beautifully. Dark brown hair with caramel highlights is one strong example of how strategically placed color can revolutionize an entire mane of hair.